Spark-coil



J. F. CAVANAGH.

SPARK COIL.

APPLlcAlon HLED Aue. 15. w13.

1,303,162. Patented May 1919;

ma Yawrm UNITED sTATEs PATENT oEErcE.

JOHN F. CAVANAGH, OF MERIDEN, CONNECTICUT, ASSIGNOR TO THE CONNECTICUT TELEPHONE & ELECTRIC CO.. INC., OF MERIDEN. CONNECTICUT, A CORPORATION OF CONNECTICUT.

SPARK-COIL.

Specification of Letters Patent.

kPatented May 6', 191e.

Application led August 15, 1918. Serial No. 250,017.

To all Uzom it muy conc-cwi.'

Be 1t known that I. JOHN F. CAvAxAGH, a c1t1zen oi' the United States of America, re-

" siding at Meriden, Connecticut, have inventcoil for ignition purposes and the objects n ately which I have had in mind have been to gain increased electrical eiliciency, to improve the magnetic circuit of the coil structure andato simplify theconstruction of the coil.

In accordance with my invention the primary winding is placed outside the second ary winding and a magnetic shell for the return magnetic circuit is provided immedisurrounding the secondary winding, the condenser being located outside this magnetic shell and the whole being incased in a. suitable protective casing. This outerV cas- I ing may also be made of magnetic material to -form a parallel return path for the magnetic circuit.

The details of construction and other features of the invention will become apparent as the specification proceeds.

In the drawing I have illustrated my invention embodied in two of vits practical forms, this with the understanding however that the invention is susceptible of various modifications without departure from the true spirit and scope thereof.

In this drawing:

Figure 1, is a longitudinal sectional view of a coil embodying the features of the invention and constructed with an outer casing of magnetic material.

Fig. 2, is a cross sectional view of the same taken substantially on the plane of the line 2 2 of Fig. 1.

Fig. 3. is a vertical sectional view Similar to Fig. 1. of a second form of invention having an outer casing of insulating or nonmagnetic material.

The core of the coil which may be made up of iron wire, as customary. is vdesignated 5. the secondary winding is designated 6, and the primary winding 7.

The secondary winding is applied directly to the core` and the primary winding is applied on the. cut-side of the secondary. the

two windings being separated from' each being separated insulating mate- Immediately around the primary winding is a magnetic element'in the 'nature of a shell l8 which may be for instance of soft Norway iron. Thisv magnetic element provides a return path for the `magnetic circuit and being located immediately adjacent the primary is very effective. The secondary in this construction being located adjacent the core is subjected to the strongest'portion of the vmagnetic field.

Outside the magnetic shell is a condenser 9. the same being shown as made up in coil form entirely shell. This places the condenser at a point relatively far removed from the influence of the secondary winding and at the outer coolest portion of the structure. The capacity therefore will remain substantially constant, inasmuch Vas the temperature will not vary to a large extent at this outside point:

The condenser is preferably protected by a suitable casing, the( same being shown in the first form as an outer magnetic shell 10. This outer shell forms a part of the magnetic return circuit, acting in parallel with the inner magnetic element. v L

The ends of the coil structure are protected by end caps 11 and 12 preferably of insulating material which maybe held together clamped in engagement with the surrounding the magneticv out-er casing bv means ofa through bolt 13 and securing nuts 14 and 15.

The second form of the invention illustrated, is similar in general respects to the first form, the main distinctionbeing that the outer casing 16 instead of being of magnetic material, is of non-magnetic material, such as a suitable insulating compound. In this case the magnetic shell 8 constitutes the only magnetic return and 'it is for this reason made somewhat heavier or of greater mass than the magnetic shell in the first form, as illustrated. n

Suitable terminals for the primary and secondary circuits are provided. which may be mounted on the insulating end caps as illustrated at 17, 18 and 19. v

The advantages of the invention will be apparent to those skilled in tl11s art, 1t bemg seen that the secondary and primary'are so disposed with respect to the magnetlc core and the surroundin magnetic shell as to obtainthe greatest e ciency from both en d the condenser is so located as to be practically unaifected by the secondary and to be maintained at as near a uniform temperature as possible and therefore of practically` a constant capacity. The coil of this' construction also is easily assembled and can be noutside said magnetic shell.

2. In a spark coil, the combination of a magnetic core, a secondary on said core, a primary about said-secondary, a magnetic element surrounding and in closerelation to said primary and a condenser outside and surrounding said magnetic shell.

3. In a spark coil, the combination of a magnetic core, a seconda-ry on said core, a primary surrounding said secondary, a magnetic element immediately urrounding said primary, a condenser outside said magnetic shell and an outer casing inclosing the entire structure. l

4. In a spark coil, the combination of a magnetic core, a secondary on said core, a primary surrounding said secondary, a magnetic element immediately surrounding said primary, a condenser surrounding said magnetic shell and a casing surrounding said condenser.

5. A structure of the character set forth in claim 4, wherein' the outer casing also is of magnetic material, said magnetic outer casing and inner magnetic element serving as part of parallel return magnetic circuits.

6. In a spark coil, a magnetic core, a secondary Winding on said core and subject to the maximum magnetic field, a primary Winding surrounding the secondary, a magnetic element immediately surrounding the primary and providing a return magnetic circuit and a condenser outside said magnetic' element "and removed from the influence of the secondary.

7. In a spark coil, the combination of a secondary winding, a primary Winding surrounding sai/d secondary Winding, a magnetic element immediately surrounding said primary Winding and a condenser outside said magnetic element.

8. In a spark coil, the combination of a secondary Winding, a primary Winding surrounding said secondary Winding,` a magnetic element immediately surrounding said primary Winding, a condensersurrounding said magnetic element and acasing inclosing said condenser and the parts Within the same.

9. In a spark coil, a secondary Winding, a primary Winding surrounding said secondar)y Winding, a magnetic element immediately inclosing said primary Winding, a condenser outside saidrmagnetic element, 1a casing inclosing said condenser and end caps engaged with said casing and closing the end portions of the coil structure.

JOHN F. CAVANAGH. 

